LINEAR TET ELEMENTS
LINEAR TET ELEMENTS
(OP)
Do u know why when plotting contour stresse of linear tet elements (which I usually avoid except for first run or displacements only) there are several color bands (stress levels)across the element.
I thought linear displacement interpolation should give constant stress across the element because stress is the derivative of the displacement?
Thank You
I thought linear displacement interpolation should give constant stress across the element because stress is the derivative of the displacement?
Thank You





RE: LINEAR TET ELEMENTS
Are you plotting average nodal stresses? If so then a stress variation across an element face is quite normal, so try plotting the un-averaged element stresses instead.
RE: LINEAR TET ELEMENTS
Thank you
RE: LINEAR TET ELEMENTS
RE: LINEAR TET ELEMENTS
"The rendering routine that plots the contours knows nothing about linear or parabolic elements" makes it clear.
I do not think they taught us the rendering routine in FEA courses.
Thank you.
RE: LINEAR TET ELEMENTS
A basic course on FEA should have covered the theory of FEA, but may not have gone far into the "art" and practice of effective FEA.
Modern post-processors will give you a great deal of control over contour plotting etc. We usually like to see a node-averaged stress plot for final results, because it looks more reasonable than an un-averaged plot. (In general, we expect stresses to vary gradually across a structure, not to jump in discrete increments.)
However, looking at the un-averaged stresses plots is usually a very important part of the verification process. If element stress differences are excessive between adjacent elements, this can be a sign that your mesh is too coarse, or possibly you have some modelling errors. If the stress differences are OK, then you may prefer to revert to averaged stress plots to produce better-looking graphics for final reporting etc.
RE: LINEAR TET ELEMENTS
http://web.peoriadesignweb.com/eos
RE: LINEAR TET ELEMENTS
You could perhaps only justify their use in an exceptionally large complex model (which cannot be easily simplified) where the degrees of freedom in a parabolic tet model would be beyond your computer resources.
RE: LINEAR TET ELEMENTS
corus
RE: LINEAR TET ELEMENTS
Regards.
RE: LINEAR TET ELEMENTS
I agree. By first run I did not mean that I will use the results. I meant that I will check the model for singularities, etc with linear tet before I convert them to parabolic tet. This saves meshing/solve time.
RE: LINEAR TET ELEMENTS
corus